What do you think is the most important issue in American politics today? Criminal justice reform? Health care? Global climate change? Immigration? Gay rights? Economic justice? ISIS? Creeping totalitarianism?

All of those things (and more!) are incredibly important, but they may all be secondary to something else: gerrymandering. And earlier this week, the Supreme Court announced that it was going to decide a case that could potentially reform the practice entirely.

For those not familiar with the term, gerrymandering is the process by which state legislators draw voting district boundaries, for both congressional and state legislature districts. That sounds pretty boring, but in essence the power to draw voting district boundaries is, in many situations, akin to the power to determine who wins elections.

This process usually happens every 10 years, and the party in control of the state legislature is, in most states, the one that’s in charge. In theory, re-drawing boundaries happens in order to balance the districts with population changes. Every 10 years, the census data is released, so if a district has grown in size, then the boundaries need to change so that each district in the state has roughly the same number of voters.

However, as computing power has grown and big data has become ubiquitous, the party in power often uses all that it knows about voters to re-draw the lines to its advantage. To illustrate how pernicious this can be, let’s consider two different situations involving a state with 200 voters, divided into five districts – so, 40 voters in each.

Scenario 1: The voters are split 116 Democrat to 84 Republican. It would make reasonable sense for the five districts to be split proportionately, producing three Democrats and two Republicans in office.

If all of these voters vote according to how the legislators expect them to – and the legislators know an awful lot about us to be able to accurately predict these things – this 116-to-84 Democratic state will produce a four-to-one Republican split.

Scenario 2: The voters are split 105 Democrat to 95 Republican. With this almost-even division, a three-to-two split favoring either party would be entirely reasonable.

But, with super-precise gerrymandering, the Democrats could give themselves control over the entire state:

With this split, the Democrats could have five-zero control of the state.

If the districts in either of these scenarios followed natural geographic or political boundaries, then it would be hard to complain. That would just be where people live and how they’ve arranged themselves on their own, so the district representation would follow naturally.

However, with gerrymandering, district lines are usually being drawn in ways that do not mirror natural dividing lines. Rather, the district lines look like fantastical beasts that often bring together people who have nothing in common other than that some politician in the state capital drew a border putting them together. Here you can see some truly incredibly drawn districts.

So now you might be thinking: That’s sort of interesting, but how does it top all of the issues mentioned in the first paragraph? Because gerrymandering leads to distorted representation in legislatures on all political issues. For instance, an overwhelming majority of people don’t like the new health care plan, but the Republicans in the House who voted for it don’t have to fear their wrath because they aren’t in their districts – thanks to gerrymandering. In other words, the people may feel one way, but politicians don’t have to listen to them.

Which brings us to the Supreme Court this week. The case before the court, arising out of Wisconsin, alleges that the state Republican-controlled legislature re-drew the district lines in 2010 in an extremely partisan way. As evidence, the challengers claim that the state as a whole voted for President Obama in 2012, but the individual districts within the state didn’t change from extreme Republican control.

On Monday, the Supreme Court agreed to review the lower court ruling that struck down the Wisconsin map as an unconstitutional partisan gerrymander. Stated plainly, the lower court said that it was not fair to those not in the dominant party that the district lines were drawn to suppress their political views.

The Supreme Court won’t hear arguments in this case until the fall, and likely won’t decide the case until next year. But when it does, it could rule that state district lines have to be drawn more fairly to represent the will of the voters of the state.

However, the Court might very well let us all down by deciding that partisan gerrymandering is perfectly constitutional. Or, it could throw its hands up and, as it has in similar cases in the past, rule that courts have to stay out of this issue because there are no manageable standards to decide such complicated issues (which would effectively be the same as saying it’s constitutional).

A ruling for the status quo would leave politics in the same state as now. But a ruling against partisan gerrymandering would have the potential to reshape every single area of American politics for generations.